1. Field of the Invention
The present invention relates to detection of the status of a plurality of position designating devices of different types which are used in a coordinates input apparatus, and more particularly to a system for detecting the status and type of each of the position designating devices which has designated only a position at which coordinates are to be input.
2. Description of the Related Art
Hitherto, a system has been incorporated in a coordinates input apparatus for detecting the status (hereinafter referred to as the "pen-down status") of a position designating device which has designated only a position on a tablet at which coordinates are to be input. The arrangement of this system has been such that a switching means is provided in the position designating device and is turned on (or off) only in the pen-down status, and that timing signals based on the ON (or OFF) condition of the switching means are transmitted to a position detecting circuit via a cord or by the use of ultrasonic waves or infrared rays.
However, with the arrangement in that timing signals are transmitted from the position designating device via a cord, there has been a drawback in that the cord causes a hindrance to the operating efficiency of the position designating device. In addition, with the arrangement in that timing signals are transmitted by the use of ultrasonic waves or infrared rays, a transmitter, a signal generating circuit, a battery, and the like must be provided in the position designating device per se. Hence, the above-described conventional arrangement involved the following problems. The arrangement of the position designating device becomes complicated and large in size and weight, thereby lowering the operating efficiency of the position designating device. In addition, there has been no means to differentiate, with ease, between a plurality of position designating devices of different types.